Regardless of whether you play entry level free online poker or high stakes Vegas A-A and K-K are the top two hands preflop that will get your heart thumping with excitement every (rare) time they appear.
When you have AA or KK the chances of a lesser pair winning pre-river are only about 20% with unpaired hands being even lower. With K-K, an A-X (Ace with any card) has a 25% to 30% chance of winning, and this is usually only if they hit the Ace.
When you have AA or KK you hear that voice saying "raise, raise, raise!" Yes, raise heavily it tells you, after all the only hands willing to call us will be ones like AK and AQ, plus a heavy raise will scare off the suited connectors that might be able to crack us later if they hit straights or flushes.
So what you do is raise, especially from a late position, and reraise any raises. Then your hope, if you reraise, is that your opponents are intending to reraise again with a weaker hand which they think is the favorite, like for example A-K or A-Q, and so you can set them all-in, or move all-in yourself.
But there are times when it pays to be more subtle than just doing the raise and reraise thing. An example is this: Suppose you have A-A in early position, and you raise. All the rest fold. How many times have you been frustrated when you raise or move all-in with those big pairs preflop only to bait no customers?
So in early position, if that's what you intend to do - if you want to catch them spilling many of their chips into your stack preflop, then just call, then wish - wish! - that someone raises after you so you can reraise. If they fold, at least you have obtained more chips than if you raised immediately and you scared them off. If they call, that's beyond preflop play already...
But this "beyond preflop play" is very significant, in that there is a big difference between A-A and K-K. Usually you should be willing to move all-in preflop more often with K-K than A-A. Why?
Because if you have A-A and the flop comes, say, Q-7-3 or K-9-5, those willing to square off with you are those with, like, A-Q, K-Q or K-J.
They are willing to feed their chips to you with these hands, and you can call their big bets or all-ins.
Your A-A is still the best hand, while they think their large (big but not big enough) pair is strong, and that hand's already a significant underdog. A-A is good for trapping as well as for speeding.
You can move all-in with it preflop, of course, but as above you can trap with it if you feel like it.
But if you have K-K, the flop might fall A-7-2, K-K, no matter how golden, is now drawing almost dead. There are two Kings left, and anyone who might be there with you may bet large because he has an Ace. (Is he likely to bet with a single Seven?)
So you have to fold your K-K, no matter how hard it is for you to get so good a hand and then banish it a few moments later. Or just call, call, call.
So, preflop, you may have to play K-K more strongly than you would play your A-A. Ideally, if you move all-in with K-K, an A-X will call you, or a small pocket pair and you'll be an approximately 75-25 favorite. (You're not likely to be called with K-X or Q-X because they're not so strong enough for calling all-ins.)
If you get called with A-X, they still have to catch the Ace. They're the ones taking the risk, and not you. If you play K-K slowly, and they ride their A-X with you on the Flop, and they caught the Ace, it's a thousandfold different from having to catch it. They have no risks to take.
There might be times where there is A-A versus K-K, but these times are rare. And if you're the one with the K-K, you might even fold it.
Say two of you in a preflop hand are the chip leaders in a tournament, and you reraise his early-position raise, then all of a sudden he pushes you all-in! You might put him on A-A, and you fold, very, very smartly and sickly. Or he's a player whom you know who will not raise that LARGE an amount unless he has A-A. But these times are rare, remember.
So, excepting some special considerations that must be remembered with the K-K, playing A-A and K-K preflop is just almost identical.
